Snap lock device for plastic parts



Nov. 15, 1966 F. TAUsslG 3,285,637

SNAP LOCK DEVICE FOR PLASTIC PARTS Filed March 6, 1964.

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5)J .5 ArroEm/Es United States Patent O 3,285,637 SNAP .LOCK DEVICE FOR PLASTIC PARTS Frederick Taussig, St. Louis, Mo., assignor to Aruudale Manufacturers, Inc., St. Louis, Mo., a corporation of Missouri Filed Mar. 6, 1964, Ser. No. 349,882 3 Claims. (Cl. 287-2032) This invention relates .to a locking device for two plastic parts. The invention is particularly applicable lfor joini-ng together pieces of nylon, polyethylene, polypropylene, and other wax-like compounds that cannot readily be joined by rsolvents or adhesives.

The locking device h-as Iinteriitting elements formed on each of the parts during the molding thereof. Upon removal of the parts from their molded cavities, and before the plastic has cooled and set, the plastic has enough resilience and ygive to permit interlocking of the locking device elements. After the plastic has cooled and become rigid, the design of the locking device elements ho'lds them in interlocking relation. The only way to separate the parts is to break them.

This locking device may be used as a permanent lock between any molded plastic parts. An exam-ple of two such parts is illustrated in this application. These include a lter for a clothes dryer and a handle for the ilter he'ld between these parts by the locking device.

Several of these locking devices -are used between the lil-ter land the handle parts. In each locking device, there is a hook member on one of the parts and an opening through the other part for receiving the hook member. One side of the opening is dene-d by a thin tab that must yield before the hook member can pass through the opening. The parts are interlocked by passing the hooks through the openings immediately upon removing the parts from their mold cavities. When the thin tabs are hot, they will yield to permit passage of the hook members. Shortly thereafter, the plastic on both parts cools and becomes rigid, and the then rigid tabs prevent the hook 'members from being removed from the openings.

The general object of this invention is to provide a locking device for two plastic parts that lis constructed to .permit inter-locking of opposing ele-ments on the two parts when they are hot, such as immediately upon removal of the parts `from a mold cavity, wherein the locking device permanently fastens the two parts together once they have cooled.

Another object of the invention is t-o provide a locking device for two plastic parts that can be molded directly to the parts.

Still another object of the invention is to provide a `locking device for two plastic parts that is so constructed that a third part may be inserted between the two plastic parts and held there when the par-ts are locked together.

Yet another object of the invention is to provide a locking device for two plastic par-ts that is of such a permanent locking nature that, to separate the parts, they must be broken. This Ifeature -of the locking device is import-ant when visible evidence that parts have been separated is desired.

Other objects and advantages will be apparent to those skilled in the art.

In the drawing:

FIGURE l is a bott-om plan view of a clothes dryer filter and handle held together by locking devices of this invention;

3,285,637 Patented Nov. 1.5, 1966 ICC without the handle as viewed vfrom the left of FIGURE 4;

FIGURE 6 is a plan view of a felt seal that may be used between the lilter and the handle;

FIGURE 7 is a view in section taken along the line 7-7 of FIGURE 5;

FIGURE 8 is a view in section on an enlarged scale taken l,r1-ong the line s s of FIGURE 2; and

' to the end 26 of the frame.

FIGURE 9 is a view in section on an enlarged scale taken along the `line 9-9 o-f'FIG'URE 2.

Refer-ring now to the drawing, this filter 20 comprises a fra-me 21 and a handle 22. The tra-me `21 and the handle 22 are formed entirely of injection molded plastic. The frame 21 may be of any size lor shape, and as illustrated, is rectangular with sides 23 and 24, and ends 25 and 26. A dish-shaped wire mesh screen 27 has -its outer edges joined -t-o the :frame 21 during the molding process. There may be reinforcing plastic ribs 28 extending trom the end 25 across the :center'of the screen to the other end 26.

There is a downwardly extending plate or wall 30 joined The wall 30 is preferably about 1A; inch thick between opposing flat sides 31 and 32. The wall 30 Iis a-t right angles t-o the plane of the frame 21.

The handle 22 comprises a .grab bar 35. Two arms 36 and 37 connect the lgrab bar to a plate 38 that has a surface 39 parallel to the wall 30.

There are a plurality of hook members 40, 41, 42 and 43 projecting from the surface 39 of the lplate 38. Each hook member 40-43 has a wall portion 44 extending at right angles from the surface 39 of the plate 38, with a hook 45 at the cuter end of the wall portion. Each hook 45 extends to one side only of the wall portion 44 and has a curved outer surface 46 that intersects a straight inner `sur-face 47. Each wall portion 44 is about 1/16 inch thick and about 5/8 inch Wide. The straight surface 47 projects slightly less than JAG inch beyond the wall portion 44. As shown in FIGURES 3 and 9, the hooks 45 on alternate yhook members 40-43 extend in opposite directions.

There are a plurality of rectangular openings 50, 51, 52 .and 53 through the wall 30 on the frame 21. These openings 50-53 correspond in position to the positions of the hooks 40-43. One side 54 of each ope-ning 50-53 has a beveled edge 55 from Ithe side 32 of the wall 31. A tab 56 extends `from the opposite side 57 of each opening 50-53, the 'free edge 58 of the tab 56 terminating about 1A@ inch yfrom the side 54. Each tab 56 is about W16 inch wide from the edge 58 to the side 57 and is between 1/32 and %4 inch thick.

For this lter 20thereV is a felt seal 60 fitting between the frame 21 .and the handle 22. The :felt .seal 60 has holes 61, 62, 63 and 64 through Iit spaced corresponding to the spacing of hook mem-ber 40-43. The felt seal 60 is somewhat larger than the plates 30 and 38.

The frame ,21 and Ihandle 22 are assembled immediately .following molding of these parts. When the parts are removed from the mold cavities, the felt seal 60 is mounted on the plate 38 with the hook members 40-43 projecting .through the holes 61-64. Then the hook ends 45 of the hook members 40-43 are pressed through the openings 50-53 in the plate 30.

Since the plastic is still hot from molding, the tabs 56 will yield when they are `pressed by the hook members 40-43. Also, the hook members 40-43 will bend according to forces applied to them.

As each hook member 40-43 is inserted into one of the openings 50-53, its curved outer Vends 46 contacts the o posing beveled edge 55. As the hook member is pressed further through the opening, its curved outer end 46 contacts the tab 56 and deects that tab, permitting the hook member to pass completely -through the opening. `As soon as the surface 47 reaches the end of the opening, the resilience of the ta-b 56 causes it to snap back to its original position and swing the hook member over to the tinal l-ocking position, as illustrated in FIGURE 9. Shortly thereafter, the plastic cools and becomes re'latively rigid. This causes the tabs 56 to lose their resilience a-nd maintain a fixed position holding lthe hook members in place with the surfaces 47 -overlying the surface 31 adjacent the -openings 50-53. Thus the l-ock cannot be broken unless the parts are physically severed.

The sizes of parts may ibe varied as required by the kinds of obje-cts being locked together. It will be apparent that the presence of the felt seal I60 requires extension o f the wall 44 so that the felt seal will be compressed while still occupying space between the plates 30 an-d 38.- Dilferent numbers of hook members and openings 50-53 may be used, depending upon the size of parts. In all cases, the alternately directed lhook members 40-43 provide a stronger lock that resists relatively sliding of the parts.

Various changes and modifications may be made Within the purview of this invention as will be readily apparent to those :skilled in the art. tions are within the scope and teaching of this invention as defined by the claims appended thereto.

What is claimed is:

1. A locking device for two plastic parts comprising a pair of hook members on one part, a wall on the other Such `changes and moditicapart, .a pair of holes through the wall positioned complementary t-o the positions of the -hook members, the hook members each havin-g a shank portion for extending through .a hole far enough to .position yan end of the shank beyond the wall, each hook member having a laterally projecting ho-ok portion on the last-named end of the shank porti-on, the hook portions Ibeing oppositely Afacing and 4being positioned for contacting the surfaces of the wall beyond the holes, the portions olf the wall which dene the .sid-es of the holes opposite the hook portions being formed as taibs extending at substantially right angles to the shank portions, the tabs being yieldable when the hooks are passed through the hole, the parts being molded plastic, the oppositely directed hook portions preventing the parts from sliding laterally to tEree the hook portions from the holes.

2. The devi-ce of claim 1 wherein one of the parts is a filter frame and the other part is a handle structure for attachment to the frame.

3. The device of claim 2 wherein the handle structure also has a plate yfacing the wall, and a felt seal between the wall an-d the plate having `holes thr-ou-gh which the shank portions extend, and havin-g `a border margin exten-ding beyond the peripheral edges of the wall and the plate.

References Cited bythe Examiner UNITED STATES PATENTS 419,846 1/ 1890 `Gamble 292-303 1,930,560 10/ 1933 Heidel 292-318 1,981,334 11/'1934 Schmaly 264-2149 2,847,731 y8/ 1958 Hollander 20-92 3,182,367 5/ 1965 Hamann et all 16-125 X .FOREIGN PATENTS 476,629 9/ 1951 Canada.

865,776 4/ 1961 Great Britain.

HARRISON R. MOSELEY Primary Examiner. P. M. CAUN, Assistant Examiner. 

1. A LOCKING DEVICE FOR TWO PLASTIC PARTS COMPRISING A PAIR OF HOOK MEMBERS ON ONE PART, A WALL ON THE OTHER PART, A PAIR OF HOLES THROUGH THE WALL POSITIONED COMPLEMENTARY TO THE POSITIONS OF THE HOOK MEMBERS, THE HOOK MEMBERS EACH HAVING A SHANK PORTION FOR EXTENDING THROUGH A HOLE FAR ENOUGH TO POSITION AN END OF THE SHANK BEYOND THE WALL, EACH HOOK MEMBER HAVING A LATERALLY PROJECTING HOOK PORTION ON THE LAST-NAMED END OF THE SHANK PORTION, THE HOOK PORTIONS BEING OPPOSITELY FACING AND BEING POSITIONED FOR CONTACTING THE SURFACES OF THE WALL BEYOND THE HOLES, THE PORTIONS OF THE WALL WHICH DEFINE THE SIDES OF THE HOLES OPPOSITE THE HOOK PORTIONS BEING FORMED AS TABS EXTENDING AT SUBSTANTIALLY RIGHT ANGLES TO THE SHANK PORTIONS, THE TABS BEING YIELDABLE WHEN THE HOOKS ARE PASSED THROUGH THE HOLE, THE PARTS BEING MOLDED PLASTIC, THE OPPOSITELY DIRECTED HOOK PORTIONS PREVENTING THE PARTS FROM SLIDING LATERALLY TO FREE THE HOOK PORTIONS FROM THE HOLES. 